1. Field of the Invention
The present invention generally relates to a mask frame assembly for depositing a thin film, and more particularly, to a mask frame assembly configured to facilitate evaporation of cleaning liquid used in a cleaning process.
2. Description of the Related Art
Organic light-emitting diode displays have wide viewing angles, good contrast, and quick response times.
In organic light-emitting diode displays, colors are displayed by using light generated as holes and electrons injected through an anode and a cathode recombine in a light-emitting layer. For this purpose, organic light-emitting diode displays have a stacked structure in which a light-emitting layer is disposed between an anode and a cathode. To obtain high light emitting efficiency, intermediate layers such as an electron injection layer, an electron transport layer, an hole injection layer, and a hole transport layer may be selectively disposed between the electrodes and the light-emitting layer.
Electrodes, intermediate layers, and light-emitting layers of organic light-emitting diode displays can be formed by various methods, such as a deposition method. In a process of manufacturing an organic light-emitting diode display by using a deposition method, a mask having a pattern corresponding to a pattern of a thin film to be formed on a substrate is prepared, and a thin film deposited on the substrate is patterned using the mask. A single large mask, which is coupled to a frame and which includes a thin-film pattern corresponding to a pattern to be formed on the entire surface of a substrate, may be used, or a mask including a plurality of segment masks having a stick shape and attached to a frame may be used.
After the deposition process is performed using a mask, the mask is cleaned and dried for the next deposition process. That is, since a deposition material is attached to the mask during the deposition process, the assembly of the mask and a frame is cleaned using cleaning liquid and is dried by blowing air through an air knife, so that the assembly of the mask and the frame can be used in a subsequent process.
However, in the cleaning and drying processes, cleaning liquid does not readily dry in fine gaps between the mask and the frame. More specifically, since the mask frame assembly is formed by welding an end of the mask to the frame, cleaning liquid permeated in the fine gaps between the mask and the frame does not readily dry even though the drying process is performed using an air knife.
If the mask frame assembly in which cleaning liquid remains is used in a subsequent deposition process, the deposition process may not be precisely performed because of the remaining cleaning liquid. For example, if the mask frame assembly in which cleaning liquid remains is mounted in a deposition chamber, the vacuum degree of the deposition chamber may vary due to the remaining cleaning liquid, and thus deposition quality may deteriorate. For this reason, it may be necessary to wait a long time until the mask frame assembly is completely dried before performing a subsequent deposition process.
In this case, as a result of the delay in reusing the assembly, operation efficiency is lowered. Therefore, countermeasures are necessary.